The present invention relates to a micro-electronic component, incorporating asynchronous digital processing means and a contact-free electromagnetic coupling interface.
It belongs to the technical field of integrated micro-electronic components, and more particularly of circuits which incorporate clock-free microprocessors (which are also known as asynchronous), and contact-free (radio-frequency) electromagnetic coupling interfaces, which are used to supply to the elements of the component, and/or to transfer data by induction to a remote station.
It is applicable in autonomous sensors/actuators with integrated digital processing, telemetry systems (industrial and biomedical applications etc.), smart cards which incorporate a microprocessor or a dedicated circuit, portable objects which are used for access control, telephony or payment, with electromagnetic coupling with a remote station.
Micro-electronic components are already known which incorporate in the same circuit digital processing means and a contact-free electromagnetic coupling interface.
For example, in application FR-A-2 735 929, the applicant describes a smart card, the micro-electronic component of which incorporates all the functional elements of the smart card. A coil (also known as the antenna, self or inductive resistor) is integrated for supply by induction to the component and for inductive transfer of data to a remote station. In integrated technology, the component additionally comprises a module for rectification of the high-frequency alternating signal which is transferred by induction by the remote station, and a module for demodulation of the direct signal which is rectified by the module for rectification, in order to retrieve the data transmitted by the remote station. The component also incorporates a module for modulation of the alternating signal at the terminals of the coil, for transmission of data to the remote station. Finally, the component incorporates a memory, and means for reading/writing of data in said memory.
In a known micro-electronic component of this type, the means for reading/writing use logic with a clock, i.e. reading/writing of the data is timed by a global, regular clock, which is generally supplied by the remote station.
The disadvantage of logic of this type with a global, regular clock, consists in the fact that it needs the clock continually, in order to scan for the presence of data to be emitted or received. As a result, logic of this type with a clock dissipates energy unnecessarily, whereas this energy is generally the most critical resource in an autonomous portable object, and the consumption of which should advantageously be limited.
An object of the present invention is to eliminate the disadvantages referred to above.
It relates to a micro-electronic component for a portable object, of the type which incorporates digital processing means, and an interface for contact-free electromagnetic coupling with a remote station.
According to a general definition of the invention, the digital processing means can operate according to a operating mode of the request/acknowledgement type, which is substantially insensitive to the propagation time, and does not have a global, regular clock, and the component additionally comprises adapter means, which can adapt the signals of the contact-free interface to the signals of the digital processing means and vice versa, in order to permit two-way dialogue with the remote station.
According to the invention, clock-free logic provides many advantages compared with logic with a clock.
Firstly, control of the electrical activity of clock-free logic is more flexible, since only the availability of the data to be processed gives rise to processing, and thus to dynamic electrical consumption. The component according to the invention can thus be put on standby for data, without consuming energy.
Secondly, the power which is consumed by clock-free logic is lower, since only the parts of the asynchronous digital processing means which are involved in the processing consume power. The energy consumed thus reflects the complexity of the processing. On the other hand, in clock-type logic, all the parts of the integrated circuit consume energy during processing (with the exception of circuits with a controlled clock, the design of which is problematic).
Thirdly, functioning in relation to the supply voltage is more reliable in the component according to the invention. In fact, the component continues to be functional within a broad voltage range, and only the processing speed varies. Clock-free circuits thus operate at the maximum speed permitted by the supply voltage.
Fourthly, the supply control unit can carry out distribution of the energy available, by taking advantage of the operating reliability of clock-free circuits. For example, the control unit can give precedence to the contact-free interface supply, which is sensitive to variations in voltage, to the detriment of the supply to the clock-free digital part, which is insensitive to these variations.
Finally, fifthly, the adoption of clock-free circuits makes it possible to authorise processing during communications, since the risk of scrambling of the communication interface, caused by the emission of the electromagnetic circuit waves, is limited, because the said clock-free digital circuits have low electromagnetic emission.
According to a preferred embodiment of the invention, the contact-free interface comprises a coil for supply by induction to the component, and/or for inductive transfer of data to the remote station.
Advantageously, the coil is produced using flat integrated technology on the component.
Thus, the component according to the invention makes it possible to integrate on a single integrated circuit means for asynchronous digital processing, and a communication interface which can be coupled electromagnetically with a remote station, with all the passive elements of the contact-free interface (including the coil). However, the invention also applies to a coil produced according to the technology wherein a coil is assembled on the component.